I am working a model similar in concept to the sign problem in Lesson 15 of the 2009 Flow Simulation Training Manual. I was able to solve the flow model and performed the tools/export results to simulation task. I next opened a new Simulation study, went into study properties, clicked the Fluid Pressure option and found the button on the choose the "Include fluid pressure effects from Solidworks Flow Simulation" was grayed out.

I opened Flow Lesson 15, ran the flow analysis, exported the results, started a Simulation study and WAS able to import the load from the Flow solution. So problem must be with my model. The flow results look resonable.